title: Allosteric coupling in the bacterial adhesive protein FimH.
abstract: The protein FimH is expressed by the majority of commensal and uropathogenic strains of Escherichia coli on the tips of type 1 fimbriae and mediates adhesion via a catch bond to its ligand mannose. Crystal structures of FimH show an allosteric conformational change, but it remains unclear whether all of the observed structural differences are part of the allosteric mechanism. Here we use the protein structural analysis tool RosettaDesign combined with human insight to identify and synthesize 10 mutations in four regions that we predicted would stabilize one of the conformations of that region. The function of each variant was characterized by measuring binding to the ligand mannose, whereas the allosteric state was determined using a conformation-specific monoclonal antibody. These studies demonstrated that each region investigated was indeed part of the FimH allosteric mechanism. However, the studies strongly suggested that some regions were more tightly coupled to mannose binding and others to antibody binding. In addition, we identified many FimH variants that appear locked in the low affinity state. Knowledge of regulatory sites outside the active and effector sites as well as the ability to make FimH variants locked in the low affinity state may be crucial to the future development of novel antiadhesive and antimicrobial therapies using allosteric regulation to inhibit FimH.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington 98195-5061, USA.
authors.forename: Victoria B
authors.initials: VB
authors.lastname: Rodriguez
authors.forename: Brian A
authors.initials: BA
authors.lastname: Kidd
authors.forename: Gianluca
authors.initials: G
authors.lastname: Interlandi
authors.forename: Veronika
authors.initials: V
authors.lastname: Tchesnokova
authors.forename: Evgeni V
authors.initials: EV
authors.lastname: Sokurenko
authors.forename: Wendy E
authors.initials: WE
authors.lastname: Thomas
mesh_terms: D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D000494:Allosteric Regulation; D000911:Antibodies, Monoclonal / Q000378:metabolism; D018360:Crystallography, X-Ray; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism; D006801:Humans; D037102:Lectins / Q000737:chemistry; D008024:Ligands; D008358:Mannose / Q000378:metabolism; D008954:Models, Biological; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D018830:Adhesins, Escherichia coli; D000911:Antibodies, Monoclonal; D037102:Lectins; D008024:Ligands; D050505:Mutant Proteins; C058769:fimH protein, E coli; D036781:Fimbriae Proteins; D008358:Mannose
keywords: Allosteric Regulation; Bacterial Adhesion; Carbohydrate-binding Protein; Catch Bonds; Protein Conformation; Protein Design